import type { DataSource } from 'typeorm';
/**
 * A PostgreSQL advisory-lock key, using either its single-key or two-key form.
 * A single key must be a int64.
 * A two key form must be int32, int32.
 */
export type SessionAdvisoryLockKey = number | {
    namespace: number;
    key: number;
};
/** Whether a session-level advisory lock is exclusive or may be shared. */
export type SessionAdvisoryLockMode = 'excl' | 'shared';
export type SessionAdvisoryLockAcquisition = 'blocking' | 'try-lock';
/** The outcome of attempting to acquire a non-blocking session-level advisory lock. */
export type SessionAdvisoryLockResult<T> = {
    acquired: false;
} | {
    acquired: true;
    value: T;
};
/** Options for a session-level advisory lock that waits until it is acquired. */
export type BlockingSessionAdvisoryLockOptions = {
    acquisition: 'blocking';
    /** Defaults to exclusive */
    mode?: SessionAdvisoryLockMode;
};
/** Options for a session-level advisory lock that returns immediately when it is held. */
export type NonBlockingSessionAdvisoryLockOptions = {
    acquisition: 'non-blocking';
    /** Defaults to exclusive */
    mode?: SessionAdvisoryLockMode;
};
/**
 * Runs a callback while holding a PostgreSQL session-level advisory lock identified by one key.
 *
 * @typeParam T - The value returned by the callback.
 * @param dataSource - The PostgreSQL TypeORM data source used to create the lock-owning session.
 * @param acquisition - Whether to wait for the lock or return immediately when it is held.
 * @param mode - Whether the lock is exclusive or shared.
 * @param key - The single PostgreSQL advisory-lock key.
 * @param callback - Work to execute after the lock is acquired.
 */
export declare function advisoryLock<T>(dataSource: DataSource, acquisition: 'try-lock', mode: SessionAdvisoryLockMode, key: number, callback: () => Promise<T> | T): Promise<SessionAdvisoryLockResult<T>>;
/**
 * Runs a callback while holding a PostgreSQL session-level advisory lock identified by two keys.
 *
 * @typeParam T - The value returned by the callback.
 * @param dataSource - The PostgreSQL TypeORM data source used to create the lock-owning session.
 * @param acquisition - Whether to wait for the lock or return immediately when it is held.
 * @param mode - Whether the lock is exclusive or shared.
 * @param namespace - The first key, used as the application's lock namespace.
 * @param key - The second PostgreSQL advisory-lock key within the namespace.
 * @param callback - Work to execute after the lock is acquired.
 */
export declare function advisoryLock<T>(dataSource: DataSource, acquisition: 'try-lock', mode: SessionAdvisoryLockMode, namespace: number, key: number, callback: () => Promise<T> | T): Promise<SessionAdvisoryLockResult<T>>;
/**
 * Runs a callback while holding a blocking PostgreSQL session-level advisory lock identified by one key.
 *
 * @typeParam T - The value returned by the callback.
 * @param dataSource - The PostgreSQL TypeORM data source used to create the lock-owning session.
 * @param acquisition - Waits for the lock; must be `'blocking'`.
 * @param mode - Whether the lock is exclusive or shared.
 * @param key - The single PostgreSQL advisory-lock key.
 * @param callback - Work to execute after the lock is acquired.
 */
export declare function advisoryLock<T>(dataSource: DataSource, acquisition: 'blocking', mode: SessionAdvisoryLockMode, key: number, callback: () => Promise<T> | T): Promise<T>;
/**
 * Runs a callback while holding a blocking PostgreSQL session-level advisory lock identified by two keys.
 *
 * @typeParam T - The value returned by the callback.
 * @param dataSource - The PostgreSQL TypeORM data source used to create the lock-owning session.
 * @param acquisition - Waits for the lock; must be `'blocking'`.
 * @param mode - Whether the lock is exclusive or shared.
 * @param namespace - The first key, used as the application's lock namespace.
 * @param key - The second PostgreSQL advisory-lock key within the namespace.
 * @param callback - Work to execute after the lock is acquired.
 */
export declare function advisoryLock<T>(dataSource: DataSource, acquisition: 'blocking', mode: SessionAdvisoryLockMode, namespace: number, key: number, callback: () => Promise<T> | T): Promise<T>;
/**
 * Attempts to run a callback while holding a PostgreSQL session-level advisory lock identified by one key.
 *
 * @typeParam T - The value returned by the callback.
 * @param dataSource - The PostgreSQL TypeORM data source used to create the lock-owning session.
 * @param mode - Whether the lock is exclusive or shared.
 * @param key - The single PostgreSQL advisory-lock key.
 * @param callback - Work to execute after the lock is acquired.
 */
export declare function tryAdvisoryLock<T>(dataSource: DataSource, mode: SessionAdvisoryLockMode, key: number, callback: () => Promise<T> | T): Promise<SessionAdvisoryLockResult<T>>;
/**
 * Attempts to run a callback while holding a PostgreSQL session-level advisory lock identified by two keys.
 *
 * @typeParam T - The value returned by the callback.
 * @param dataSource - The PostgreSQL TypeORM data source used to create the lock-owning session.
 * @param mode - Whether the lock is exclusive or shared.
 * @param namespace - The first key, used as the application's lock namespace.
 * @param key - The second PostgreSQL advisory-lock key within the namespace.
 * @param callback - Work to execute after the lock is acquired.
 */
export declare function tryAdvisoryLock<T>(dataSource: DataSource, mode: SessionAdvisoryLockMode, namespace: number, key: number, callback: () => Promise<T> | T): Promise<SessionAdvisoryLockResult<T>>;